Determination of liver‐specific r2* of a highly monodisperse USPIO by 59Fe iron core‐labeling in mice at 3 T MRI. (30th July 2014)

• Record Type: Journal Article
• Authors: Raabe, Nina; Forberich, Evelyn; Freund, Barbara; Bruns, Oliver T.; Heine, Markus; Kaul, Michael G.; Tromsdorf, Ulrich; Herich, Lena; Nielsen, Peter; Reimer, Rudolph; Hohenberg, Heinrich; Weller, Horst; Schumacher, U.; Adam, Gerhard; Ittrich, Harald
• Is Part Of: Contrast media & molecular imaging. Volume 10:Number 2(2015:Mar./Apr.)
• Page Start: 153
• Page End: 162
• Publication Date: 2014-07-30
• Subjects: Diagnostic imaging -- Periodicals; Magnetic resonance imaging -- Periodicals; Contrast media (Diagnostic imaging) -- Periodicals; Contrast Media -- Periodicals; Diagnostic Imaging -- Periodicals; Substances de contraste -- Périodiques; Diagnostics moléculaires -- Périodiques; Imagerie médicale; Substance de contraste; Périodique électronique (Descripteur de forme); Ressource Internet (Descripteur de forme); 616.0754
• DOI: 10.1002/cmmi.1612
• Languages: English
• ISSNs: 1555-4309

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>Accurate determination of tissue concentration of ultrasmall superparamagnetic iron oxide nanoparticles (USPIO) using <italic>T</italic><sub>2</sub>* MR relaxometry is still challenging. We present a reliable quantification method for local USPIO amount with the estimation of the liver specific relaxivity <italic>r</italic><sub>2</sub>* using monodisperse <sup>59</sup>Fe‐core‐labeled USPIO (<sup>59</sup>FeUSPIO). Dynamic and relaxometric <italic>in vivo</italic> characteristics of unlabeled monodisperse USPIO were determined in MRI at 3 T. The <italic>in vivo</italic> MR studies were performed for liver tissue with <sup>59</sup>FeUSPIO using iron dosages of 9 (<italic>n =</italic> 3), 18 (<italic>n =</italic> 2) and 27 (<italic>n =</italic> 3) µmol Fe kg<sup>−1</sup> body weight. The <italic>R</italic><sub>2</sub>* of the liver before and after USPIO injection (∆<italic>R</italic><sub>2</sub>*) was measured and correlated with <sup>59</sup>Fe activity measurements of excised organs by a whole body radioactivity counter (HAMCO) to define the dependency of ∆<italic>R</italic><sub>2</sub>* and <sup>59</sup>FeUSPIO liver concentration and calculate the <italic>r</italic><sub>2</sub>* of <sup>59</sup>FeUSPIO for the liver. Ultrastructural analysis of liver uptake was performed by histology and transmission electron microscopy. ∆<italic>R</italic><sub>2</sub>* of the liver revealed a dosage‐dependent accumulation of <sup>59</sup>FeUSPIO with a percentage uptake of 70–88% of the injection dose. Hepatic ∆<italic>R</italic><sub>2</sub>* showed a dose‐dependent linear correlation to <sup>59</sup>FeUSPIO activity measurements (<italic>r =</italic> 0.92) and an <italic>r</italic><sub>2</sub>* in the liver of 481 ± 74.9 m<sc>m</sc><sup>−1</sup> s<sup>−1</sup> in comparison to an <italic>in vitro r</italic><sub>2</sub>* of 60.5 ± 3.3 m<sc>m</sc><sup>−1</sup> s<sup>−1</sup>. Our results indicate that core‐labeled <sup>59</sup>FeUSPIO can be used to quantify the local amount of USPIO and to estimate the liver‐specific relaxivity <italic>r</italic><sub>2</sub>*. Copyright © 2014 John Wiley & Sons, Ltd.</p> </abstract>